This invention relates to the field of solid-state hydride materials, and more particularly to solid-state hydride materials encapsulated in a hydrogen permeable shell and a method for forming and handling same. The thusly formed capsules are useful in applications involved with hydrogen storage and generation, such as military (hydrogen storage for stationary and mobile power sources, remote power, low signature power), aerospace (hydrogen for auxiliary fuel cell power), automotive (hydrogen for fuel cell and combustion engines), commercial (hydrogen for stationary fuel cells for distributed power), and consumer (hydrogen for fuel cell powered portable electronic devices).
Chemical hydrides release hydrogen exothermically which, for thermodynamic reasons, means that they cannot be rehydrogenated (i.e., refueled or recycled) simply by supplying hydrogen to the dehydrogenated material. Therefore, the spent hydride usually must be removed from the point-of-use and transported to a reprocessing facility. Recovering, transporting, and returning these chemical hydride materials can be difficult. Chemical hydrides based on hydrolysis reactions (i.e., reaction with water) are typically formulated as liquids or slurries and therefore, are relatively easily handled by standard pumping techniques. However, chemical hydrides based on solid-state hydride/hydroxide reactions are formulated as dry powders, which make handling difficult. In addition, controlling the hydrogen release reaction of bulk powders that release hydrogen exothermically is also difficult. Many nominally reversible metal hydrides may also benefit from being removed from their point-of-use and reprocessed, i.e., rehydrogenated, at a dedicated reprocessing facility. As an example, LiAlH4, Li3AlH6, and AlH3 all require excessively high hydrogen pressures for rehydrogenation.
Therefore, it would be advantageous to have a practical form factor and method for making the hydrides in a designed form factor so that the spent (dehydrogenated) products of these hydrides can be practically removed from their point-of-use and then reprocessed at a reprocessing facility.